A variety of materials have been employed for patches to widen obstructed right ventricular (RV) outflow tracts in patients with tetralogy of Fallot. These materials have included Teflon, preclotted Dacron, parietal pericardium, and dura mater. Autologous parietal pericardium has the advantage of being readily available, and does not present the problem of suture-line bleeding, which often occurs with the synthetic patches. Both tissue and synthetic patches utilized in the RV outflow tract may become aneurysmal if the RV peak systolic pressure is not returned to normal or near normal levels after operation. Although the intimal lining tissue of the synthetic patch may calcify, the synthetic material itself does not. In contrast, autologous patch material may calcify. Such was the case in the 16-year-old boy described in this report.